Environmental hazards
Understanding why natural hazards occur can help countries to manage or prevent their consequences. Case studies illustrate the impact of natural hazards in the short and long term.
Environmental hazards
What is a 'natural hazard'?
A natural hazard is the threat of a naturally occurring event happening in a particular area often without warning, which has negative impacts on people and the landscape. Examples of natural hazards include tropical storms, earthquakes, volcanoes and tsunamis.
Globally, natural disasters kill 60,000 people per year, on average.
Tropical storms
Location
Tropical storms are found between the equator and the Tropic of Cancer in the northern hemisphere and between the equator and the Tropic of Capricorn in the southern hemisphere.
They originate over the eastern side of oceans and move westwards where, when they cross land, they cause great devastation before dying out. Tropical storms over 74mph are called hurricanes in the USA, cyclones in India and typhoons in China and Japan.
The main features of tropical storms
Causes of tropical storms
In order for a tropical storm to form, the following conditions need to be met:
- sea temperatures must be over 27°C
- low air pressure
- air spiralling upwards
- large expanse of water
- location between the tropics
- damp, moist air with humidity greater than 60% per cent